Multiple choice

The speed of the boat in still water is 6 kmph and the speed of the stream is 1.5 kmph. A man rows to a place at a distance of 22.5 km and comes back to the starting point. The total time taken by him-

  1. 10 hours

  2. 4 hours 10 minutes

  3. 6 hours 10 minutes

  4. 8 hours

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Speed downstream = 6 + 1.5 = 7.5 km/h. Speed upstream = 6 - 1.5 = 4.5 km/h. Time to go 22.5 km downstream = 22.5/7.5 = 3 hours. Time to return upstream = 22.5/4.5 = 5 hours. Total time = 3 + 5 = 8 hours.